The present invention relates to an electrode plate for a color display excellent in chemical resistance and in adhesive properties, a method for manufacturing the same, and a color display that uses the electrode plate.
An electrode plate used for a color display is generally manufactured such that a color filter made from organic resin is formed on a glass substrate, an organic protective film similarly made from organic resin is then applied thereonto, and an inorganic transparent electrode having electric conductivity is formed. The conductive line of the transparent electrode is generally installed such that a uniformly transparent conductive film is first formed, and then wet etching is performed to obtain a desired conductive line shape.
When the wet etching is performed for conductive line processing, various chemicals are used, and therefore there occurs a situation in which the color filter or the transparent organic protective film, which is laid underneath the transparent conductive film, is corroded and invaded by the chemicals. In addition, since the inorganic conductive film is formed on the organic resin film, it is very difficult to give sufficient adhesive properties to be able to endure predetermined processing.
Therefore, conventionally, chemical resistance and adhesive properties have been improved by forming other thin films (silicon dioxide thin films are generally used) between the color filter or the organic protective film and the inorganic conductive film. However, an RF sputtering technique according to which the silicon dioxide thin films are formed has an industrial disadvantage in the fact that film formation speed is slow. Additionally, the RF-plasma prior to forming the silicon dioxide thin film causes the color filter or the organic protective film to receive physical/chemical damage, thus mainly causing instability occurring when electrode plates are manufactured at a post-step (i.e., step of forming the inorganic conductive film after forming the color filter and the organic protective film on the glass substrate).
Further, in order to solve the aforementioned problems, the present inventors have previously invented an electrode plate, etc., capable of preventing physical/chemical damage of a color filter or an organic protective film and capable of improving adhesive properties with an inorganic conductive film by colliding a gas ion that includes an oxygen ion or an argon ion with the color filter or the organic protective film so as to form a layer, in which the color filter or the organic protective film is at least partially carbonized, between the color filter or the organic protective film and the transparent conductive film (Japanese Unexamined Patent Publication No. H 10-10518). Further, in the invention described in this publication, the present inventors have disclosed an Embodiment in which ions are emitted with an ion gun in a vacuum atmosphere as a method for colliding the gas ion that includes the oxygen ion or the argon ion with the color filter or the organic protective film.
According to the invention described in Japanese Unexamined Patent Publication No. H10-10518 that has been made by the present inventors, a layer that has been at least partially carbonized is formed on a color filter or on an organic protective film, and thereby the chemical resistance and adhesive properties of the color filter or the organic protective film can be enormously improved without forming a transparent inorganic thin film, such as a silicon dioxide thin film, which has been conventionally required, on these films, and a transparent electrode film (inorganic conductive film) with a desired pattern has come to be easily processed.
However, since the method performed by the present inventors includes a step of processing under a vacuum atmosphere, it is difficult to process a large amount of electrode plate materials under the vacuum, and, disadvantageously, this leads to a decrease in productivity. Additionally, since the method includes processing under the vacuum, an expensive apparatus is required to manufacture the electrode plate. Therefore, disadvantageously, this raises the manufacturing costs of products to be obtained.
It is therefore an object of the present invention to obtain a manufacturing method for an electrode plate for a color display according to which a color filter or an organic protective film is more easily prevented from receiving physical/chemical damage and according to which adhesive properties with a conductive film are improved. Another object of the present invention is to, in the manufacturing method for the electrode plate, protect a color filter or an organic protective film in an easier way when a transparent conductive film is formed by wet etching. Still another object of the present invention is to obtain an electrode plate for a color display that does not use a transparent inorganic thin film like a silicon dioxide thin film, which has generally conventionally been used, between a color filter or an organic protective film and an inorganic conductive thin film, and is to obtain a color display using the electrode plate.
The aforementioned problems of the present invention are solved by the following manufacturing methods (1) and (2), by an electrode plate for a color display obtained by these manufacturing methods, and by a color display that uses the electrode plate.
(1) A method for manufacturing an electrode plate for a color display by sequentially forming a color filter and a transparent conductive film on a substrate, comprising the steps of: forming a color filter on a substrate; thereafter forming a layer in which said color filter is at least partially carbonized through processing that uses a discharge under a dry atmosphere having substantially atmospheric pressure; and
forming a transparent conductive film on the partially carbonized color filter layer.
(2) A method for manufacturing an electrode plate for a color display by sequentially forming a color filter, an organic protective film for protecting the color filter, and a transparent conductive film on a substrate, comprising of: sequentially forming a color filter and an organic protective film on a substrate; thereafter forming an at least partially carbonized layer on said organic protective film through processing that uses a discharge under a dry atmosphere having substantially atmospheric pressure; and forming a transparent conductive film on the partially carbonized organic protective film.
According to the invention of the method (1), by performing processing that uses a discharge under a dry atmosphere having substantially atmospheric pressure, a partially carbonized color filter layer can be formed on a color filter without the necessity of expensive vacuum processing equipment, and, as a result, the color filter is prevented from receiving physical/chemical damage, and adhesive properties with the transparent conductive film (inorganic conductive film) formed thereon can be improved.
Similarly, according to the invention of the method (2), by performing the processing that uses a discharge under a dry atmosphere having substantially atmospheric pressure, a partially carbonized organic protective film layer can be formed on an organic protective film without the necessity of expensive vacuum processing equipment, and, as a result, the organic protective film is prevented from receiving physical/chemical damage, and adhesive properties with the transparent conductive film (inorganic conductive film) formed thereon can be improved.
If carbonization that uses a discharge is applied onto a color filter or onto an organic protective film under an ordinary atmospheric pressure, the color filter or the organic protective film will receive chemical damage, and, as a result, an electrode plate for a color display that is inferior in alkali resistance will be produced. However, the present inventors pre-dry the atmosphere, and perform processing that uses a corona discharge or perform atmospheric plasma treatment in that atmosphere. Thereby, the present inventors have found that the color filter or the organic protective film is prevented from receiving physical/chemical damage, and adhesive properties with the transparent conductive film formed thereon can be improved, and have completed the present invention.
It is difficult to, at present, give a clear description of a technical reason for the aforementioned phenomenon found by the present inventors. Presumably, it seems that water molecules contained in an ordinary atmosphere are ionized by a corona discharge or by atmospheric plasma, so as to exert some physical or chemical adverse influence on a color filter or on an organic protective film.
The term xe2x80x9csubstantially atmospheric pressurexe2x80x9d mentioned herein means atmospheric pressure or pressure that has been reduced within a structurally reasonable range of processing equipment that uses a discharge in order to facilitate the start/continuance of the discharge.
There are various possible methods in order to obtain a dry atmosphere having substantially atmospheric pressure. The easiest method is to provide such a processing tank as to cover a necessary part of a processing unit that uses a discharge of the processing equipment and to purge the inside thereof by dry air through a moisture absorbing agent or by dry gas used in a process.
From the viewpoint that a discharge device is handy/universal or can perform consecutive processing, processing that uses a corona discharge or atmospheric plasma processing is preferably used as processing that uses the discharge.
When the corona discharge processing is performed, a general discharge processing unit that includes a discharge electrode, a dielectric, and a high frequency power-supply unit can be used. Concerning the processing condition of the corona discharge, its optimum condition depends on the structure of the discharge-processing unit. Desirably, the output is 0.1 kW to 1.5 kW, and, more desirably, 0.2 kW to 1.2 kW. If processing that uses an extremely excessive discharge is performed, a color filter and an organic protective film will be damaged, and physical, chemical durability might be deteriorated on the contrary.
Concerning the distance between a discharge electrode and a substrate with a color filter or a substrate in which a color filter is coated with an organic protective film, its optimum condition depends on the structure of a device for discharge processing. If less than 5 mm, the color filter or the organic protective film will be damaged, and the physical, chemical durability of an obtained film that includes a carbonized layer will be deteriorated on the contrary. Special limitations are not imposed on the processing time that uses a discharge, except that at least a part of the surface of a color filter or an organic protective film can be substantially carbonized during the processing time. However, there is a case in which carbonization increases excessively when the processing time using the discharge exceeds one minute.
When the atmospheric plasma processing is performed, a general discharge processing unit that is made up of a power-supply unit, a discharge electrode, a gas-introducing tube, a chamber, etc., can be used. This discharge-processing unit is provided with a pair of opposing surfaces, at least one of which is provided with a solid dielectric. A pair of metal electrodes is disposed in the vicinity of the other one of the pair of surfaces, and a space between the metal electrodes through which a color filter or an organic protective film can be passed is provided. A voltage is applied between the electrodes while the color filter or the organic protective film is passing therebetween, so as to generate plasma.
A pulsed electric field, as well as an AC waveform, can be used as an electric field applied between the electrodes. Concerning the processing condition of the atmospheric plasma processing, its optimum condition depends on the structure of the discharge-processing unit. If processing that uses an extremely excessive discharge is performed, a color filter and an organic protective film will be damaged, and physical, chemical durability might be deteriorated on the contrary.
Processing gas used for the atmospheric plasma processing is not limited to a specific one. For example, argon, helium, nitrogen, air, oxygen, etc., can be mentioned as the processing gas. Rare gases, such as argon and helium, are more desirable because they do not exert a great influence on the color filter and on the organic protective film, and can perform stable processing. These may be used as a single gas or as a mixture of two or more gases.
Desirably, the acceleration voltage is 5 kV to 20 kV, and, more desirably, 8 kV to 15 kV. If processing that uses an extremely excessive discharge is performed, the color filter and the organic protective film will be damaged, and physical, chemical durability might be deteriorated on the contrary. Special limitations are not imposed on the processing time, except that the surface of the film to be processed can be substantially carbonized during the processing time. However, there is the possibility that carbonization will increase excessively when the processing time using the discharge exceeds one minute.
Desirably, in the present invention of the aforementioned methods (1) and (2), an adherent layer made of any of the compounds of a metallic oxide, a metallic nitride, and a metallic oxynitride is disposed between the transparent conductive film and the partially carbonized layer, in order to improve the adhesive properties between the transparent conductive film and the partially carbonized layer.
Since the adhesive properties between the transparent conductive film and the partially carbonized layer are improved by disposing an adherent layer made of any of the compounds of a metallic oxide, a metallic nitride, and a metallic oxynitride between the transparent conductive film and the partially carbonized layer, the form accuracy of an end of the conductive line pattern obtained when an electrode conductive line pattern by wet etching is formed is more reliably improved in comparison with a case where the adherent layer is not disposed. This means that the margin of the optimum processing condition of the processing using the discharge extends.
A transparent metallic oxide film, a transparent metallic nitride film, and a transparent metallic acid nitride film, such as silicon dioxide, tantalate, aluminum oxide, silicon nitride, acid silicon nitride, titanium oxide, and zirconia, can be mentioned as the adherent layer made of any of the compounds of a metallic oxide, a metallic nitride, and a metallic oxynitride. A vacuum deposition method, a DC magnetron sputtering method, a RF magnetron sputtering method, etc., are used as the film formation method for the adherent layer. In consideration of an influence on the partially carbonized layer given when the film is formed or in consideration of easy applicability to the enlargement of the substrate, a desirable method is a film formation method for the adherent layer of silicon dioxide, tantalate, silicon nitride, or acid silicon nitride that uses the DC magnetron sputtering method. A voltage to be applied onto a cathode may be continuously applied, or may be pulsedly applied. Any of the aforementioned electric-charge applying methods is appropriately selected in accordance with the component of a selected adherent layer.
In the present invention of the methods (1) and (2), the ratio (Ic-c/Icoo) of a signal (Ic-c) resulting from a Cxe2x80x94C bond to a signal (Icoo) resulting from a carboxyl group according to X-ray photoelectron spectroscopy in the carbonized layer may be set to be greater than that in a color filter or an organic protective film that has not been carbonized.
In the electrode plate for the color display of the present invention, the fact that the ratio (Ic-c/Icoo) of the carbonized layer is greater than that of the color filter or the organic protective film that has not been carbonized means that a carbonized layer has been formed.
The partially carbonized layer of the present invention is not necessarily required to be a uniformly carbonized layer. The carbonized layer may be nonuniform in thickness as long as it has chemical resistance more than a required level. However, it is undesirable that the carbonized layer is extremely thick, because the carbonized layer absorbs visible light, and thereby transmittance decreases. Further, it is undesirable that carbonization extremely advances, because the adhesive properties between the carbonized layer and the thin film layer formed thereon are diminished.
A color filter, which is an aim of the present invention, can be made from any resin, as long as it is a resin that transmits light having a predetermined wavelength independently of a film formation method or a coloring method. Further, an organic protective film, which is an aim of the present invention, is generally made from an acrylic resin, a polyimide resin, an epoxy resin, or a mixture of these resins. However, it can be made from any resin, as long as protective properties to be an object of the present invention are satisfied thereby.
A film in which a complex oxide that includes at least two of indium, tin, and zinc, a zinc oxide doped with tin or aluminum, or a metal film that includes at least one of gold, silver, copper, and platinum that have low electric resistance is sandwiched by a transparent metallic oxide film like an indium oxide is used as a transparent conductive film that can be used in the present invention. However, any material can be used, as long as it is a conductive film that has transparency, which is an aim of the present invention. A material to be used is not limited to a specific one.
The electrode plate for the color display of the present invention has sections shown in FIG. 1 through FIG. 4. In the electrode plate of the present invention, an at least partially carbonized layer between a color filter or an organic protective film and a transparent electrode or an at least partially carbonized layer between a color filter or an organic protective film and an adherent layer serves to protect a base placed thereunder from suffering physical/chemical damage.
According to the present invention, chemical resistance/adhesive properties required in post-processing can be greatly improved by using an electrode plate for a color display provided with a color filter or provided with an organic protective film whose surface has been carbonized at least partially. The at least partially carbonized surface can be formed by corona discharge or by plasma processing under substantially atmospheric pressure. This makes it unnecessary to use processing equipment which is expensive and is incapable of performing a huge amount of processing because of the processing conventionally carried out under a vacuum atmosphere, and, as a result, manufacturing costs can be reduced.